package nio;

import org.junit.Test;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;

/**
 * 非阻塞式
 */
public class NonBlockingTest {
    @Test
    public void client() throws Exception {
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
        // 切换非阻塞模式
        socketChannel.configureBlocking(false);

        ByteBuffer buf = ByteBuffer.allocate(1024);

        buf.put((new Date().toString()).getBytes());
        buf.flip();
        socketChannel.write(buf);
        buf.clear();

        socketChannel.close();
    }

    @Test
    public void server() throws Exception {
        // 1. 获取通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        // 2. 切换为非阻塞模式
        serverSocketChannel.configureBlocking(false);
        // 3. 绑定端口
        serverSocketChannel.bind(new InetSocketAddress(9898));
        // 4. 获取选择器
        Selector selector = Selector.open();
        // 5. 将通道注册到选择器上，并指定“监听接收事件”
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        // 6. 轮训式的获取选择器上已经“准备就绪”的事件
        while (selector.select() > 0) {
            // 7. 获取当前选择器中所有注册的“选择键（已就绪的监听事件）”
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();

            while (it.hasNext()) {
                // 8. 获取准备就绪的事件
                SelectionKey sk = it.next();

                // 9. 判断具体的是什么事件就绪
                if (sk.isAcceptable()) {
                    // 10.　若“接受就绪”，获取客户端通道
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    // 11. 切换非阻塞模式
                    socketChannel.configureBlocking(false);
                    // 12. 将通道注册到选择器上
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (sk.isReadable()) {
                    // 13. 获取当前选择器上“读就绪”状态的通道
                    SocketChannel socketChannel = (SocketChannel) sk.channel();

                    // 14. 读取数据
                    ByteBuffer buf = ByteBuffer.allocate(1024);
                    int len = -1;
                    while ((len = socketChannel.read(buf)) != -1) {
                        buf.flip();
                        System.out.println(new String(buf.array(), 0, len));
                        buf.clear();
                    }
                }

                // 15. 取消选择键
                it.remove();
            }
        }
    }
}
